Effects of Electric Current
There are three effects of electric current. They are magnetic effect, heating effect, and chemical effect. When an electric current flows through a wire a magnetic field is generated around the wire and this can be determined by the deflection of a compass. The magnetic field has a direction along with a magnitude. If the electric current flows in a direction north to south the direction in which the magnetic compass will deflect is clockwise implying that the direction of the magnetic field is dependent on the direction of flow of the electric current. Conventionally it is taken that magnetic lines emerge from the north pole and merge at the south pole. Magnetic field lines from two magnets cannot cross each other. The magnitude of the magnetic field increases with the increase of electric current through the wire. The SI unit of the magnetic field is Tesla.
Electricity and magnetism are bound to each other, and it is proven that it produces a magnetic effect when the electric current passes through the copper wire.
Magnetic Field
The magnetic field is a quantity that has magnitude as well as direction.
A magnetic field's direction is usually taken as the direction in which a compass needle's north pole travels inside it.
The convention is for the field lines to emerge from the north pole and merge at the south pole.
No two-magnet bar field lines are found to cross one another. If this occurs, it implies that the compass needle will point to two directions at the point of intersection, which is not feasible.
With the increase of current through the wire, the magnitude of the magnetic field produced by an electric current at a given point increases.
Right-Hand Thumb Rule
The right-hand thumb rule, also known as Maxwell's corkscrew law, describes the direction of the magnetic field associated with a current-carrying conductor.
Right - hand thumb rule states that "Imagine holding current with a straight conductor in your right hand, so the thumb points in the current direction. Then curl your conductive fingers towards the magnetic field lines.
Fleming’s Left-Hand Rule
Fleming's left-hand rule says, "Stretch the left thumb, forefinger and middle finger to be perpendicular to each other. If the first finger points in the direction of the magnetic field and the second finger in the direction of the current, the thumb points in the direction of motion or the driver's force.”
The human body also produces a magnetic field, but it is minimal and about one-billionth of the magnetic field on earth.
The heart and brain are the two main organs in the human body that created the magnetic field.
The magnetic field within the human body forms the basis for obtaining images of various parts of the body.
The technique used to get the body part image is known as MRI Magnetic Resonance Imaging.
Electric Motor
An electric motor is a rotating system designed to transform electric power into mechanical power.
We have hundreds of appliances that use electric motors, such as fridges, mixers, fans, washing machines, computers, etc.
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Commercial and high-performance motors are used as−
1. An electromagnet instead of a permanent magnet.
2. A Large number of conductive wires turns in the coil bearing electrical current.
The soft iron core wound is known as an armature, with the coil wound and the coils wounded.
The armature has the main function to maximize engine power.
Fleming’s Right-Hand Rule
Fleming’s right-hand rule states that “Extend the right thumb, forefinger and middle finger in order to be perpendicular to each other.
If the forefinger indicates the magnetic field direction and the thumb indicates the conductor's motion direction, then the middle finger indicates the direction of the induced current.
Electric Generator
A generator of electricity is a device that converts mechanical energy into electric energy.
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Mechanical energy is used in an electric generator to rotate the conductor in a magnetic field, as a result, this electricity is produced.
FAQs on Magnetic Effects of Electric Current
1. What is the magnetic effect of electric current?
The magnetic effect of electric current is the phenomenon where a magnetic field is produced around a conductor when an electric current flows through it. This discovery, made by Hans Christian Oersted, established the relationship between electricity and magnetism. The strength of the magnetic field depends on the amount of current flowing through the conductor.
2. What are magnetic field lines and their key properties?
Magnetic field lines are imaginary lines used to represent the direction and strength of a magnetic field. They have several key properties:
- They are continuous closed loops that emerge from the North pole and merge at the South pole outside the magnet, and move from South to North inside the magnet.
- The density of the field lines indicates the strength of the magnetic field; closer lines mean a stronger field.
- The tangent at any point on a field line gives the direction of the magnetic field at that point.
- Most importantly, two magnetic field lines never intersect each other.
3. Why do two magnetic field lines never cross each other?
Two magnetic field lines can never cross or intersect because if they did, it would imply that at the point of intersection, the magnetic field has two different directions. A compass needle placed at that point would point in two directions simultaneously, which is physically impossible. Therefore, magnetic field lines are always distinct and do not cross.
4. How can you determine the direction of the magnetic field around a straight current-carrying conductor?
The direction of the magnetic field produced by a straight current-carrying conductor can be determined using the Right-Hand Thumb Rule, also known as Maxwell's Corkscrew Rule. According to this rule, if you imagine holding the conductor in your right hand with your thumb pointing in the direction of the current, the direction in which your fingers curl around the conductor gives the direction of the magnetic field lines.
5. What is a solenoid and how is its magnetic field similar to a bar magnet?
A solenoid is a long coil containing a large number of close turns of an insulated copper wire. When an electric current flows through it, it produces a magnetic field that is very similar to that of a bar magnet. The magnetic field inside the solenoid is strong and nearly uniform. One end of the solenoid behaves like a North pole and the other end like a South pole, just like a bar magnet.
6. What is the difference between an electromagnet and a permanent magnet?
The primary differences between an electromagnet and a permanent magnet are:
- Nature: An electromagnet is a temporary magnet that works only when current is flowing through its coil. A permanent magnet has constant magnetic properties.
- Strength: The strength of an electromagnet can be easily changed by varying the current or the number of turns in the coil. The strength of a permanent magnet is fixed.
- Polarity: The polarity (North and South poles) of an electromagnet can be reversed by reversing the direction of the current. The polarity of a permanent magnet is fixed.
7. What is the difference between Fleming's Left-Hand Rule and Fleming's Right-Hand Rule?
Both rules relate force, magnetic field, and current, but they apply to different devices:
- Fleming's Left-Hand Rule is used for electric motors. It helps determine the direction of the force (or motion) experienced by a current-carrying conductor placed in a magnetic field.
- Fleming's Right-Hand Rule is used for electric generators. It helps determine the direction of the induced current when a conductor moves in a magnetic field.
In simple terms, the Left-Hand Rule finds the Force, while the Right-Hand Rule finds the Induced Current.
8. How does an electric motor work?
An electric motor is a device that converts electrical energy into mechanical energy. Its operation is based on the principle that a current-carrying conductor experiences a force when placed in a magnetic field. A rectangular coil (armature) is placed between the poles of a strong magnet. When current flows through the coil, opposite forces act on its two arms, creating a turning effect or torque. A split-ring commutator reverses the direction of current in the coil every half rotation, ensuring the coil continues to rotate in the same direction.
9. What is electromagnetic induction?
Electromagnetic Induction (EMI) is the phenomenon of producing an induced electric current in a closed circuit or coil by changing the magnetic field linked with it. This was discovered by Michael Faraday. A current can be induced either by moving a coil in a magnetic field or by changing the magnetic field around a stationary coil. This principle is the basis for the working of electric generators and transformers.
10. Explain the working principle of an electric generator.
An electric generator is a device that converts mechanical energy into electrical energy. It works on the principle of electromagnetic induction. When a rectangular coil is rotated mechanically in a uniform magnetic field, the magnetic flux through the coil changes continuously. This change in magnetic flux induces an electric current in the coil. The direction of this induced current is determined by Fleming's Right-Hand Rule.
11. What are the key components of a DC electric motor and their functions?
The key components of a DC electric motor are:
- Armature Coil: A rectangular coil of insulated copper wire wound on a soft iron core, which rotates when current flows through it.
- Strong Field Magnet: Provides a strong, uniform magnetic field in which the armature rotates.
- Split-Ring Commutator: A device that reverses the direction of current in the armature coil after every half rotation. This is crucial for continuous rotation.
- Brushes: Carbon or metallic conductors that press against the commutator to supply current to the armature coil from the power source.
